[PATCHv2] Optab: add isfinite_optab for __builtin_isfinite

[HAO CHEN GUI <guihaoc@linux.ibm.com>]

Hi,
  This patch adds an optab for __builtin_isfinite. The finite check can be
implemented on rs6000 by a single instruction. It needs an optab to be
expanded to the certain sequence of instructions.

  The subsequent patches will implement the expand on rs6000.

  Compared to previous version, the main change is to document isfinite
in md.texi.
https://gcc.gnu.org/pipermail/gcc-patches/2024-April/649339.html

  Bootstrapped and tested on x86 and powerpc64-linux BE and LE with no
regressions. Is this OK for trunk?

Thanks
Gui Haochen

ChangeLog
optab: Add isfinite_optab for isfinite builtin

gcc/
	* builtins.cc (interclass_mathfn_icode): Set optab to isfinite_optab
	for isfinite builtin.
	* optabs.def (isfinite_optab): New.
	* doc/md.texi (isfinite): Document.


patch.diff
diff --git a/gcc/builtins.cc b/gcc/builtins.cc
index f8d94c4b435..b8432f84020 100644
--- a/gcc/builtins.cc
+++ b/gcc/builtins.cc
@@ -2459,8 +2459,9 @@ interclass_mathfn_icode (tree arg, tree fndecl)
       errno_set = true; builtin_optab = ilogb_optab; break;
     CASE_FLT_FN (BUILT_IN_ISINF):
       builtin_optab = isinf_optab; break;
-    case BUILT_IN_ISNORMAL:
     case BUILT_IN_ISFINITE:
+      builtin_optab = isfinite_optab; break;
+    case BUILT_IN_ISNORMAL:
     CASE_FLT_FN (BUILT_IN_FINITE):
     case BUILT_IN_FINITED32:
     case BUILT_IN_FINITED64:
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index 5730bda80dc..8ed70b3feea 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -8557,6 +8557,11 @@ operand 2, greater than operand 2 or is unordered with operand 2.

 This pattern is not allowed to @code{FAIL}.

+@cindex @code{isfinite@var{m}2} instruction pattern
+@item @samp{isfinite@var{m}2}
+Set operand 0 to nonzero if operand 1 is a finite floating-point
+number and to 0 otherwise.
+
 @end table

 @end ifset
diff --git a/gcc/optabs.def b/gcc/optabs.def
index ad14f9328b9..dcd77315c2a 100644
--- a/gcc/optabs.def
+++ b/gcc/optabs.def
@@ -352,6 +352,7 @@ OPTAB_D (fmod_optab, "fmod$a3")
 OPTAB_D (hypot_optab, "hypot$a3")
 OPTAB_D (ilogb_optab, "ilogb$a2")
 OPTAB_D (isinf_optab, "isinf$a2")
+OPTAB_D (isfinite_optab, "isfinite$a2")
 OPTAB_D (issignaling_optab, "issignaling$a2")
 OPTAB_D (ldexp_optab, "ldexp$a3")
 OPTAB_D (log10_optab, "log10$a2")